There are different meanings to the word “religion.” Looked at one way, it is clear that Yoga is not a religion. Looked at another way, it can appear that Yoga can be “religious,” though remaining questionable as to whether it is “a religion.” Below are four definitions of religion, taken from the Encarta World English Dictionary, an online dictionary. Based on those definitions, is Yoga a religion? Incidentally, it is not that Encarta is the final work on the definition of religion. Rather, it has been chosen as a straightforward way of exemplifying common knowledge about religion. It is simply a dictionary, not a complex academic debate about the meaning of religion.
1) Beliefs and worship:
"People's beliefs and opinions concerning the existence, nature, and worship of a deity or deities, and divine involvement in the universe and human life"
No. Yoga does not prescribe the worship of any specific "deity or deities." The word divine is defined (in dictionaries) as coming from, or connected with God or gods. Yoga does not give specific instructions for the "existence, nature, [or] worship". Yet, Yoga acknowledges that bhakti Yoga, the path of devotion is a valid aspect of Yoga. Yoga does not tell you where to direct that devotion, or the specific methods by which you should do it. That is left to personal religious preference.
2) Particular system:
"A particular institutionalized or personal system of beliefs and practices relating to the divine"
No: Once again, divine is defined as relating to God or gods, and Yoga itself does not prescribe to what or whom one should direct their worship, nor does Yoga require it. Again, Yoga definitely acknowledges the value of bhakti Yoga, regardless of which form that takes for an individual person. It also may be true that one uses the word divine in other ways as well. Also, Yoga itself is not institutionalized as a religious system, although some of the principles are contained within many religions or other systems (such as the principles of kindness to other people, taking care of one's body, regulating breathing, or quieting the mind).
3) Beliefs or values:
"A set of strongly-held beliefs, values, and attitudes that somebody lives by"
Maybe, but not really: One could argue that Yoga is a religion by the definition of religion as being a set of strongly-held beliefs, values, and attitudes that one lives by. On the other hand, this could also apply to many other things as well, including governmental, educational, psychological, social, cultural, or familial ways of living. Common sense tells us that these are not really what is meant by the word “religion” in the context of questioning whether or not Yoga is a religion.
4) Obsession:
"An object, practice, cause, or activity that somebody is completely devoted to or obsessed by (‘The danger is that you start to make fitness a religion.’)" [Note: The ‘…danger…’ quote is in the dictionary.]
Maybe, but not really: One could become "completely devoted to or obsessed by" Yoga, and thus this use of the word religion might apply. Once again, however, common sense tells us that this is not really the meaning of the word “religion.” Most people have a working, day-to-day, common language sense of the meaning of “a religion,” and it simply does not apply to Yoga.